The invention relates to a mobile apparatus for the machining of crankshaft pins on crankshafts, and also to a method for machining crankshaft pins using that apparatus.
Devices for the machining of crankshaft pins or journals are generally known. The known apparatus includes those which consists of two divided rotating rings which are provided on the outer circumference with a sprocket-wheel toothed arrangement and are held and guided radially on transition grooves between the crankshaft pins by sliding blocks made of plastic. The drive takes place by means of a motor which is driven by compressed air, via a roller chain which has been placed around one of the rotating rings. The other rotating ring is connected to the driven rotating ring by spacer rods which can be screwed in. The machining of the running surface takes place with the rotating rings revolving, by means of a compressed-air grinding machine which is fitted onto the device and is equipped with a cup wheel. The finish-machining can take place by means of an orbital grinder fitted on the device, or manually by filing or by abrasive-grinding. Subsequently, the transition grooves must be reset using manually guided radial grinding machines driven by compressed air.
Because of the low removal efficiency during grinding, this method is uneconomical, and because of the contamination of the operating area with grinding dust which is detrimental to health, a large outlay for cleaning work is necessary.
The imprecise guiding and the play, which increases with the machining time, in the sliding blocks in the transition grooves means that a large overmeasure must be provided which is finished by complex, manual work and with reduced manufacturing quality and with a high expenditure of time.
The construction of the device and also the alignment on the crankshaft pin are time-consuming. Because a compressed-air hose follows the device and automatically coils up, it is not possible to perform a continuous working sequence, since the direction of rotation of the device must regularly be reversed in order to uncoil the hose.
DE 34 34 140 shows a device which is suspended on a mount and supported on the crankshaft pin by means of rollers or sliding blocks. The device follows the revolving crankshaft pin on account of the mount and is always maintained in a plane-parallel position with respect to the crankshaft central pin by an electronic spirit level. The machining takes place by means of a driven grinding cylinder.
In addition to the above-described disadvantages of the grinding method, in this device there is a risk of inaccuracies during the controlled parallel alignment if vibrations or oscillations occur in the vicinity of the device, and so the manufacturing quality is reduced when used, for example on ships. Furthermore, the main bearings of the crankshaft are stressed by the revolution during the machining and may be damaged.
German Utility Model 77 09 500 discloses a device consisting of a stationary, divisible outer ring which is fastened to the crankshaft web in an axially and radially adjustable manner. Mounted rotatably in this outer ring is a transmission-driven carrier ring which carries an axially displaceable slide on a guide. Fastened to this slide is a cutter for the machining of the crankshaft pin, the cutter being displaced along the running surface by an advancing device.
The construction and the installation of this device are very complicated, and require considerable time to precisely adjust the fixed outer ring.
The object of the invention is to provide a mobile device and a method for the simple, rapid and precise machining of crankshaft pins on crankshafts.
The above stated object is achieved by the apparatus and method of the invention.
The present invention is in a portable apparatus for surface machining a crankshaft pin having web side surfaces. The apparatus has a moveable tool for machining the surface and inner rings adapted for radial positioning on the crank shaft pin surface which are fixed to the web side surface. The apparatus also includes revolving rotating rings which are guided in the inner rings. The fixing segments attached to the inner rings position the inner rings on the surface.
The machining method applied with the apparatus achieves the dimensional, shape and positional tolerances specified in terms of the design, and also the required surface finish so that only a minimal amount of manual finishing work is required comparable to that required when manufacturing from new.
The particularly advantageous, simple installation and handling of the apparatus provide a considerable time savings for the machining, thereby resulting in an overall increase in the economic efficiency of the machining.
The favorable reduction in the volume of chips generated during the finish-machining means that the yield of grinding dust, which is detrimental to health, is virtually completely eliminated.
In a preferred embodiment, the apparatus is attached without the use of bores, so that after the machining there is no reduction in the strength of the crankshaft due to material being taken away or due to changes in the properties of the material. In particular, reworking of damaged crankshaft pins (for example having hardened surfaces) to a constructionally permissible undersized diameter on crankshafts incorporated in the engine is possible.
The various features of novelty which characterize the invention are pointed out with particularity in the claims appended to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects obtained by its use, reference should be had to the accompanying drawings and descriptive matter in which there is illustrated and described a preferred embodiment of the invention.